title: Reproducibility of current classifications of endometrial endometrioid glandular proliferations: further evidence supporting a simplified classification.
abstract: OBJECTIVE
  To compare the reproducibility of the current (2003) World Health Organization (WHO), endometrial intraepithelial neoplasia (EIN) and European Working Group (EWG) classifications of endometrial endometrioid proliferations.
  
  
  RESULTS
  Nine expert gynaecological pathologists from Europe and North America reviewed 198 endometrial biopsy/curettage specimens originally diagnosed as low-grade lesions. All observers were asked to classify the cases by using the categories described in each scheme: six for WHO, four for EIN, and three for EWG. The results were evaluated by kappa statistics for more than two observations. The analysis was repeated using only two major categories (benign versus atypical/carcinoma). Both the WHO and EIN classifications showed poor interobserver agreement (κ = 0.337 and κ = 0.419, respectively), whereas the EWG classification showed moderate agreement (κ = 0.530). Full agreement between pathologists occurred in only 28% for the WHO classification, 39% for the EIN classification, and 59% for the EWG classification. With only two diagnostic categories, kappa values increased in all classifications, but only the EWG classification reached a substantial level of agreement (κ = 0.621); similarly, full agreement among all pathologists increased to 70% for the WHO classification, 69% for the EIN classification, and 72% for the EWG classification.
  
  
  CONCLUSIONS
  A two-tier classification of endometrial endometrioid proliferative lesions improves reproducibility, and should be considered for the diagnosis of endometrial biopsy/curettage specimens.
authors.affiliation: Department of Pathology, CRESIB (Centre de Recerca en Salut Internacional de Barcelona), Hospital Clinic, Faculty of Medicine, University of Barcelona, Barcelona, Spain.
authors.forename: Jaume
authors.initials: J
authors.lastname: Ordi
authors.forename: Christine
authors.initials: C
authors.lastname: Bergeron
authors.forename: David
authors.initials: D
authors.lastname: Hardisson
authors.forename: W Glenn
authors.initials: WG
authors.lastname: McCluggage
authors.forename: Harry
authors.initials: H
authors.lastname: Hollema
authors.forename: Ana
authors.initials: A
authors.lastname: Felix
authors.forename: Robert A
authors.initials: RA
authors.lastname: Soslow
authors.forename: Esther
authors.initials: E
authors.lastname: Oliva
authors.forename: Fattaneh A
authors.initials: FA
authors.lastname: Tavassoli
authors.forename: Isabel
authors.initials: I
authors.lastname: Alvarado-Cabrero
authors.forename: Michael
authors.initials: M
authors.lastname: Wells
authors.forename: Francisco F
authors.initials: FF
authors.lastname: Nogales
mesh_terms: D002278:Carcinoma in Situ / Q000145:classification* / Q000473:pathology; D004714:Endometrial Hyperplasia / Q000145:classification* / Q000473:pathology; D016889:Endometrial Neoplasms / Q000145:classification* / Q000473:pathology; D005260:Female; D006801:Humans; D015588:Observer Variation; D015203:Reproducibility of Results; D014944:World Health Organization
keywords: endometrial carcinoma; endometrial hyperplasia; interobserver variability